如何访问源自数据库的ArrayList中的哈希图？

Question

I have an ArrayList with a bunch of hashmaps. Each hashmap has the name and value of a column originated from a database. How do I access the value of these columns?

The Netbeans variable inspector shows me:

avaliacaoList = (java.util.ArrayList) [{id_grade_curricular=5476, posicao=...

And the debugger presents me with the values below:

I need to iterate in the ArrayList, accessing each hashmap and his values. I tried many ways to iterate in this ArrayList, but I could not find a way to access the field id_grade_curricular (see orange arrow) of each "record". Can someone help me to achieve this? Thanks.

Answer 1

I am assuming you have a list of hashmaps and that you absolutely do need it that way.

for (HashMap h : avaliacaoList){
    Object result = h.get("id_grade_curricular");
    //do something
}

Instead of Object use whatever you are storing.

Answer 2

Remember, the items in the ArrayList are HashMaps . You have to then actually access the key:value pair you want.

for (HashMap entry : avaliacaoList){
    int value = entry.get("id_grade_curricular")
    // Do something with value here
}

Note here I'm assuming the type of the map is HashMap<string,int> since that's what your example looks like. Adjust the types accordingly if that's not true.

Answer 3

Please don't use Raw Types . You could iterate the List and call Map.get() with something like

List<HashMap<String,String>> avaliacaoList;
for (HashMap<String,String> map : avaliacaoList) {
  System.out.println(map.get("id_grade_curricular"));
}